Narrow Band Advanced Mobile Phone System (NAMPS) is an improved variant of the Advanced Mobile Phone System(AMPS) that uses narrower band radio channels.
The NAMPS mobile phone system is an analog mobile phone system introduced by Motorola for commercial use in 1991. It is an evolution of Advanced Mobile Phone Service (AMPS) and is based on the IS-88 international standard.
Unlike AMPS, N-AMPS splits the 30 kHz radio channels into three narrowband 10 kHz radio channels. This triples the transmission capacity of the N-AMPS system compared to AMPS. The radios used in NAMPS are dual- mode devices that can be used in the narrowband and widerband versions.